Electronic Spectroscopy

Characterization of the Lowest Excited States of [Rh(bpy-h8)n(bpy-d8)3-n]3+by Highly Resolved Emission and Excitation Spectra

“…For all progressions observed for the title compounds one obtains S ≈ 0.3, using the expression S = v ( I v / I v -1 ), with I v being the intensity of one member of a specific progression and v the vibrational quantum number . Nearly the same value of 0.3 has also been found for the uncoordinated bpy. , Compared to the known range of S values observed for other compoundsvalues up to 10 have been reported (for example, see refs , , −54)it follows that a Huang−Rhys factor of 0.3 must be regarded as being very small. This implies similar equilibrium positions of the hypersurfaces of the triplet state and the ground state for the complexes investigated.…”

“…(Figure , Table ) The intensity distributions of these weak progressions may be used to determine the corresponding Huang−Rhys factor S . S describes the shift of the nuclear equilibrium positions (of the potential hypersurfaces) between ground and excited states for that specific vibrational mode and may be used to determine the corresponding Franck−Condon factor. , …”

Intraligand Charge Transfer in Pt(qol)2. Characterization of Electronic States by High-Resolution Shpol'skii Spectroscopy

“…For these vibrations distinct Franck−Condon progressions are observed, for example, at 505 cm -1 ≈ 2 × 253 cm -1 , 759 cm -1 = 3 × 253 cm -1 , etc., and at 826 cm -1 = 2 × 413 cm -1 , 1236 cm -1 ≈ 3 × 413 cm -1 (Table , Figure a). The occurrence of a progression signifies a shift of the excited state potential hypersurface with respect to the one of the ground state along the normal coordinate of the specific vibration (for example, see refs −42). For the 253 cm -1 mode, the energy differences between adjacent members of the progression are constant up to at least the sixth member (within the experimental accuracy of ±1 cm -1 ).…”

“…Hence, the potential hypersurface may be regarded as harmonic at least up to 1500 cm -1 above the zero-point vibrational level. To characterize the strength of the progression, one can determine the Huang−Rhys factor S , which is related to the Franck−Condon factor. − S may be estimated using the equation S = v ( I v / I v - 1 ) (low-temperature limit; v is the vibrational quantum number, and I v is the intensity of the v th member of the progression) . An estimate of S from the first member of the respective progression ( v = 1) and the electronic origin yields for the 253 cm -1 progression S ≈ 1.0 and for the 413 cm -1 progression S ≈ 0.6.…”

Inter- and Intraconfigurational Transitions of Nd3+ in Hexafluoroelpasolite Lattices

“…If we adopt the adiabatic approximation for the vibronically coupled system, then the unpolarized intensity I if of the electronic transition from the initial 4f 3 level |f 3 Γ i 〉 to the final 4f 2 5d level |f 2 d Γ f 〉 may be expressed as where ν̄ if is the vibronic transition wavenumber, is the electric dipole operator, χ i and χ f are the initial and final vibrational states, and the summation is over the polarization q ( q = 0, ±1) and the components γ of the initial and final levels. In eq 1, the Condon approximation is also used in which the electronic transition moment is assumed to be independent of the vibrational wave functions . If we assume that only the lowest vibrational level associated with the initial electronic state is populated, then the vibrational term on the right side of eq 1 can be given by where S is the Huang−Rhys factor and n is the vibrational quantum number of the terminal vibrational state.…”